“The president is right to see flaws in [the deal] and he set a very reasonable challenge to the world,” said Johnson, arguing that the US should work with France, Germany, the UK and others to improve the deal, which was signed by the Obama administration in 2015.

“He said: ‘Look, Iran is behaving badly, has a tendency to develop intercontinental ballistic missiles. We’ve got to stop that. We’ve got to push back on what Iran is doing in the region. We’ve got to be tougher.’”